The determination of the concentration of various analytes in physiological samples is of growing importance in our society. Such samples are analysed in various fields of application for example in clinical laboratories or in “home monitoring”. In particular this also includes glucose measurement in diabetes management and the measurement of cholesterol for cardiac and vascular diseases. Medical blood diagnostics always requires that a blood sample is collected from the individual to be examined.
The analytics carried out after the lancing process are often carried out in a small portable measuring instrument a so-called “hand-held device” in which test elements wetted with blood are analysed. Measurement in these instruments is primarily carried out electrochemically or optically. In the case of the optically based measurements, the sample is illuminated with light and the reflected light is detected in order to determine the analyte concentration. Test elements such as test strips are primarily used for this purpose which are wetted with the sample such as blood or interstitial fluid. Subsequently the sample reacts with the reagents which are applied to this test element. This can lead to a change in colour which can be subsequently detected.
When conventional methods are used to analyse test elements, it is of major importance that the detection area of the test element is uniformly wetted with the test liquid. Non-uniform or inadequate wetting of the detection area can result in erroneous results. Especially when a small amount of test liquid is used, the distribution on the test element may not be uniform and only a part of the detection area is wetted with sample material. In the conventional optically-based methods of measurement the reflected light is often measured from the entire detection area which results in a high degree of inaccuracy of the measured glucose because different proportions of unwetted area enter into the determination depending on the applied amount of sample. Thus, if the detection area is inadequately wetted it may fall short of the size of measured section required for an error-free measurement. This may necessitate either a repetition of the measurement for the patient or false measured values may be generated.
Attempts to overcome inadequate or non-uniform wetting of the test element have previously not led to a satisfactory solution. In the simplest case the patient is forced to visually verify the wetting of the test element. This is not easy especially in the case of diabetics who often already have a reduced vision.
The object resulting from the disadvantages of the prior art is to develop a system which ensures simpler and more accurate analytics.